Table 2.
Characteristics of studies included in the least-squares regression model
| Author | Intervention/comparison; Level of Evidence | Study size | Graft (source) | Imaging parameters | SNQ calculation |
|---|---|---|---|---|---|
| Chen et al. [12] | Semitendinosus and gracilis (autograft) versus
doublelooped fresh-frozen tendon (allograft) Level of Evidence: III |
Autograft (N = 28: age: 29 ± 6 years); allograft (N = 20; age: 30±6 years) | (1) Semitendinosus and gracilis (autograft); (2) double-looped fresh-frozen tendon (allograft) | 3.0T MRI: sagittal imaging with PD-Fs and 3D-DESS sequences |
Evaluated at and femoral tunnel site and intra-articular tibial, mid-substance, and femoral graft sites |
| Gohil et al. [17] | Minimal debridement/remnant preservation (RP)
versus standard reconstruction Level of Evidence: I |
RP (N = 22: age: 30.5 years, range: 15–59 years); standard (N = 24; age: 35.5 years, range: 21–50) | Double-looped semitendinosus and gracilis tendon (autograft) | 1.5T MRI: TR/TE 3000/30 ms (PD-FSE); TR/TE 4000/85 ms (T2-FSE, fat suppressed); 3 mm slice thickness |
Evaluated near the femoral tunnel, graft mid-substance, near the tibial tunnel, and within tibial tunnel |
| Hakozaki et al. [18] | None (observational study) Level of Evidence: II | N = 61; age: 28.2 years, range: 13–48 years | Two double-looped semitendinosus tendons (autograft) | 1.5T MRI: TR/TE 500/18 ms (T2*WI); TR/TE 2666/22 ms (PDWI); 15 cm field of view; 4 mm slice thickness |
Evaluated at the entire intra-articular portion of the graft |
| Howell et al. [20] | Impinged versus unimpinged ACL
grafts Level of Evidence: III |
Impinged (N = 17; age: 23 years). Unimpinged (N = 15; age: 25 years) | Double-looped semitendinosus and gracilis tendon (autograft) | 1.5T MRI: TR/TE: 1200/40 ms (standard spin-echo); 3 mm slice thickness | Raw ACL graft signal
intensity. Evaluated at the proximal, middle, and distal portions of the intra-articular graft. |
| Hsu et al. [21] | None (observational study) Level of Evidence: IV |
N = 27: age: 27.2 years, range: 18–45 years | Bone–patellar tendon-bone (autograft) | 1.5T MRI | Raw ACL graft signal
intensity. Evaluated in the middle of the graft. |
| Lee et al. [24] | Remnant preservation (RP) versus remnant
sacrificing (RS) surgical techniques Level of Evidence: III |
RP (N = 56; age: 30.1 years), RS (N = 42; age: 30.4 years) | Semitendinosus and gracilis tendon (autograft) | 1.5T MRI: TR/TE 3000–4000/17–18 ms (PDWI) |
Evaluated at proximal, middle, and distal portions of the anteromedial and posterolateral bundles of the ACL graft |
| Lee et al. [25] | None (observational study) Level of Evidence: IV |
N = 247; age: 29 years, range: 18–58 years | Central quadriceps tendon–patellar bone graft (autograft) | 1.0T MRI, 1.5TMRI: Tl, TW-SE, PD-FSE fat-saturated sequences | Intra-articular raw signal intensity evaluated
at the proximal, middle, and distal portions of the graft *Note: data reported graphically as “signal intensity (ratio)” |
| Li et al. [26] | Double-looped semitendinosus and gracilis
tendon (autograft) versus tibialis anterior (allograft) Level of Evidence: III |
Autograft (N = 21; age: 29.5 ± 5.0 years), allograft (N = 17; age: 30.8 ± 5.9 years) | Double-looped semitendinosus and gracilis tendon (autograft); tibialis anterior (allograft) | 3.0T MRI: TR/TE: 3000/28 ms (PD fat saturation); TR/TE: 5730/34 ms (STIR); TR/TE: 14.1/5 ms (3D-DESS); 15 cm field of view, slice thickness 3 mm (0.6 mm for 3D-DESS) |
Evaluated as the average of the proximal, middle, and distal portions of the ACL graft |
| Liu et al. [30] | Semitendinosus and gracilis graft tibial
insertion preservation versus tibial insertion detachment Level of Evidence: I |
Insertion preservation (N = 18; age: 31.5 ± 6.6 years); insertion detachment (N = 19; age: 29.4±5.3 years) | Double-looped semitendinosus and gracilis tendon (autograft) with: tibial insertion preservation or tibial insertion detachment | 3.0T MRI: TR/TE: 3000/28 ms (PD fat saturation); TR/TE: 5730/34 ms (STIR); 15 cm field of view; 3 mm slice thickness |
Evaluated at the “graft site” |
| Min et al. [32] | None (prospective observational cohort
study) Level of Evidence: II |
N = 23; age: 32 years, range: 16–54 years | Bone-patellar tendon-bone (autograft) | 1.5T MRI: TR/TE: 20/70 (PDWI, T2WI); 14–18 cm field of view; 4 mm slice thickness | Raw signal intensity of the ACL graft |
| Muramatsu et al. [33] | Bone-patellar tendon-bone: allograft versus
autograft Level of Evidence: III |
Autograft (N = 20; age: 28.3 ± 6.3 years); allograft (N = 24; age: 26.1 ± 1.6 years) | Bone-patellar tendon-bone (autograft and allograft) | 1.0T MRI: TR/TE: 500/17 ms (T1WI) |
Evaluated at the center of the intra-articular region of the graft |
| Stockle et al. [38] | None (prospective observational
study) Level of Evidence: II |
N = 20; age 30 years, range: 17–59 years | Patellar tendon bone graft (autograft) | Native Tl/T2-weighted spin-echo (SE) sequences; contrast-enhanced (Gd-GTPA 0.1 mmol/kg body weight) dynamic gradient echo turbo flash sequences and Tl-SE and fat-saturation sequences |
Evaluated at the proximal, middle, and distal thirds of the intra-articular graft in native T1 sequences and after Gd-GTPA contrast administration |
| Author | Imaging outcomes | Imaging follow-up | Imaging findings | Clinical outcomes/evaluations | Clinical follow-up | Quality score** |
|---|---|---|---|---|---|---|
| Chen et al. [12] | (1) SNQ; (2) Graft bending angle (angle between femoral bone tunnel and line connecting femoral and tibial tunnel openings) | Autograft and allograft groups: 3, 6, and 12 months | No significant differences were observed between HS allografts and autografts during the postoperative follow-up period | (1) IKDC; (2) Lysholm knee score; (3) Tegner knee score; (4) Anterior drawer test; (5) Lachman test | Uncertain | 17 (8/1/6/1/1) |
| Gohil et al. [17] | (1) SNQ; (2) damage to PCL; (3) incidence of cyclops lesions; (4) assessment of impingement; (5) tibial tunnel placement; (6) femoral tunnel placement | 2, 6, and 12 months | HS-RP autograft signal was significantly greater than HS autografts at 2 months and significantly less than HS autografts at 6 months postoperatively | (1) Knee swelling; (2) incidence of complications; (3) range of motion, measured with goniometer; (4) stability using KT-1000 arthrometer; (5) Lachman test; (6) IKDC score; (7) one-legged hop test | 2 weeks, 2 months, 6 months, 12 months |
21 (10/1/5/5/0) |
| Hakozaki et al. [18] | (1) SNQ | 3, 6, and 12 months | MRI SNQ was significantly greater at 6 months compared to 3 and 12 months postoperative time points for HS autografts | (1) Lysholm score; (2) Tegner activity level; (3) IKDC score; (4) AP stability on KT-2000 arthrometer; (5) Pivot shift test | 12 months | 20 (10/2/5/3/0) |
| Howell et al. [20] | (1) ACL graft signal intensity; (2) tibial tunnel location | 3, 6, and 12 months (impinged: 26.9 ± 8.9 months, unimpinged: 12.4± 1.7 months) | No significant differences in HS autograft MRI signal intensity was observed throughout the first postoperative year | (1) Knee extension; (2) pivot shift test; (3) knee laxity with KT-1000 arthrometer | 12 months | 15 (7/2/4/2/0) |
| Hsu et al. [21] | (1) ACL graft signal intensity; (2) tibial tunnel width at bone plug site and aperture; (3) tibial tunnel length; (4) patellar tendon MRI signal; (5) patellar tendon thickness; (6) patellar tendon length | 3, 6, 12, and 18 months | A decreasing trend in MRI signal intensity throughout the first postoperative year was observed for BPTB autografts | None | N/A | 14 (5/2/5/2/0) |
| Lee et al. [24] | (1) SNQ; (2) frequency of interbundle high signal intensity; (3) signal intensity of ACL remnant (evaluated in RP group) | < 1 month (RP: N = 10, RS: N = 10), 2–4 months (RP: N = 19, RS:N = 11), 6–9 months (RP: N = 15, RS: N = 10), 12–18 months (RP: N = 12, RS: N = 11) | HS-RP demonstrated increased MRI SNQ at 2–4 months compared to HS grafts. HS SNQ remained constant throughout the postoperative period while HS-RP SNQ decreased significantly from 2 to 4 months postoperatively | None | N/A | 12 (5/1/4/2/0) |
| Lee et al. [25] | (1) ACL graft signal intensity ratio; (2) graft donor-site change; (3) merchant congruence angle; (4) Insall-Salvati ratio | 3–6 months (N = 36), 7–12 months (N = 26), 13–18 months (N = 14), 19–24 months (N = 7), 25–30 months (N = 8),> 31 months (N = 7) | No significant differences in QUAD graft signal intensity ratio were observed between postoperative time points | (1) Second look arthroscopy, biopsy; (2) complications; (3) donor-site morbidity; (4) range of motion; (5) Lachman test; (6) anterior drawer test; (6) pivot shift test; (7) anterior laxity on KT-1000 arthrometer; (8) quadriceps muscle strength; (9) Lysholm knee score; (10) IKDC score; (11) Shelbourne and Trumper questionnaire | 6 weeks, 3 months, 6 months, 9 months, 12 months, 18 months, 24 months, 30 months, and 36 months | 18 (9/3/3/3/0) |
| Li et al. [26] | (1) SNQ; (2) presence of ligament tears and cartilage defects | 3, 6, and 12 months | No significant differences in SNQ were observed between HS autografts and TA allografts during the postoperative period. Allograft SNQ was significantly increased at 6 months postoperatively | (1) IKDC score; (2) Lyshom Knee activity score; (3) Tegner activity score; (4) anterior drawer test; (4) Lachman test; (5) pivot shift test; (6) anterior tibial translation difference with KT-1000 knee arthrometer between healthy and reconstructed knees | 3, 6, and 12 months | 19 (9/1/5/3/1) |
| Liu et al. [30] | (1) SNQ | 3, 6, 12, and 24 months | Preservation of the tibial bone insertion of HS grafts resulted in significantly decreased SNQ at 6 and 12 months postoperatively compared to standard HS graft ACLR | (1) Range of motion; (2) anterior drawer test; (3) Lachman test; (4) pivot shift test; 5 | 3, 6, 12, and 24 months | 23 (10/1/7/5/0) |
| Min et al. [32] | (1) Signal intensity; (2) cross-sectional area of the graft | 1, 2, 3, 6, and 12 months | Signal intensity at 12 months was significantly greater than 3 months postoperatively | None | N/A | 12 (7/1/4/0/0) |
| Muramatsu et al. [33] | (1) SNQ (contrast-enhanced imaging was employed, raw values before and after enhancement were reported) | 1, 4, 6, and 12 months | BPTB autograft SNQ was significantly greater than allograft SNQ at 4 and 6 months postoperatively. Allograft SNQ increased within the 4–12 months postoperative period while autograft signal remained relatively constant | None | N/A | 17 (7/2/5/3/0) |
| Stockle et al. [38] | (1) Signal/noise ratio | 2 weeks ± 3 days, 12 weeks ± 17 days, 24 weeks ± 42 days, year ± 49 days, 2 year ± 56 days | Sequential increase in graft signal/noise ratio throughout the first postoperative year was observed, decreasing by 2 years postoperatively | (1) Lysholm score; (2) OAK score; (3) IKDC score; (4) Lachman test; (5) pivot shift test; (6) KT-1000 laxity measurements; (7) range of motion (reported as flexion/extension deficits) | 6 months, 1 year, 2 years | 14 (8/1/4/1/0) |
**
Subcomponent scores of reporting, external validity, internal validity—bias, internal validity—confounding, and power, respectively, are reported